A1 alloy films and melting A1 alloy sputtering targets for depositing A1 alloy films

ABSTRACT

An Al alloy film containing one kind or two or more kinds of alloy components selected from a group of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn in a total amount of 0.1 to 10 at %, and a melting Al alloy sputtering target for depositing the Al alloy film, wherein the above-mentioned film is used as a reflection film for an optical recording medium, a shading film for a liquid crystal display panel or for a solid image pickup device, and an Al alloy thin film line or electrode material for a semiconductor device.

This application is a continuation of Ser. No. 08/888,784 filed Jul. 7,1997 now Pat. No. 5,976,641 which is a division of Ser. No. 08/264,763filed Jun. 23, 1994 now abandon, which is a continuation of Ser. No.07/842,556 filed Feb. 27, 1992 abn.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to Al alloy films and melting Al alloysputtering targets for depositing the thin films, and particularly, toAl alloy films used as (1) shading films for liquid crystal displaypanels, solid state pickup devices (elements), etc., (2) reflectionfilms for optical recording media such as magneto-optical disks, (3) Alalloy thin film line or electrode materials for semiconductor devices,and to (4) melting Al alloy sputtering targets for depositing the thinfilms.

2. Prior Art

(1) Shading Films

(1)-(a) Recently, there has been demanded a liquid crystal display panelwith a large sized screen and high resolution. To meet the demand,active matrix system using 2-terminal or 3-terminal elements are in thedevelopment. Among them, those using thin film transistors (hereinafterreferred to as TFT) have been mainly used as the large sized and highresolution liquid crystal display panels.

Such a liquid crystal display panel is obtained by partially forming asemiconductor area of a-Si, p-Si, etc. on a transparent insulatingsubstrate of quartz, glass, etc., forming TFT's serving as switchesinside the area, and forming display bodies such as electrodes andliquid crystals used as a display panel over them. In the above, thetransparent substrate is disadvantageous in that the rays of light comeinto the semiconductor area, and a photo-excited current flows, whichmakes OFF operation insufficient. As a countermeasure for preventing thelight from coming into the semiconductor area, there is used a methodfor depositing metal films (shading films) on the upper surface, on thelower surface or on both surfaces of the TFT area to shield the light.Such shading films are used not only for shielding the semiconductorarea, but also for upgrading contrast by depositing the films into gridshaped narrow strips on the upper and lower sides of areas betweenrespective picture elements.

Refractory metals such as Cr, etc. or colored resins have been used asthe shading films. However, in such shading films for liquid crystaldisplay panels, that is, shading films of a refractory metal or acolored resin, the reflectance is low so that the light is absorbed inthe shading films, resulting in the increased temperature in the shadingfilms. Particularly, in the metal films having high thermalconductivity, temperature is easily raised inside the light-shieldedarea (the surface close to a liquid crystal area inside the shadingfilms) by the light irradiated on the outer surface of the shadingfilms, so that the liquid crystal temperature is raised, anelectrochemical reaction in the electrode interface of the liquidcrystal is expedited and the TPT OFF current is increased, therebycausing a remarkable degradation in display qualities.

As a countermeasure therefor, high reflective shading films are used inplace of the above-mentioned low reflective shading films. Au, Cu and Alare suitable for depositing the high reflective shading films, andparticularly, Al is most suitable therefor because of inexpensiveness,excellent adhesion to a substrate and facility for etching. Therefore,there have been generally used pure Al films or Al-Si alloy films (Sicontent is small). However, such pure Al films or Al-Si alloy films aredisadvantageous in that there occur hillocks due to the residual stressgenerated in the films during a depositing process or a laminatingprocess, or due to heat history generated in manufacturing the liquidcrystal display panel. Also, they have a tendency to easily produce pinholes so that, at the time of irradiation of the light, the lightthrough the pin holes activates a TFT to thereby generate an erroneouselectric signal. Furthermore, they are disadvantageous in that thetemperature is raised at the time of irradiation of the light due to thehigh thermal conductivity, thereby degrading the display quality of theliquid crystal panel. Particularly, in the projection type liquidcrystal display capable of displaying a large sized picture, which isdeveloped actively in recent years, a strong light is irradiated by ahalogen lamp, etc. in order to secure brightness, which makes thegenerations of erroneous electric signals and hillocks conspicuous.

(1)-(b) With the rapid progress of the image pickup ability, the solidstate image pickup device (element) has been strongly required toenhance its performances furthermore. A sectional view of a conventionalsolid state image pickup element is shown in FIG. 17. Shading films 5having light receiving windows in a matrix shape are deposited on asemiconductor substrate 1. The shading films 5 and a signal line 7 areoften formed in the same process, so that the pure Al films or Al-Sialloy films have been generally used. In FIG. 17, reference numerals 2is an N-type diffusion layer, 3 is an electrode, 4 is an insulating filmbetween layers and 6 is an insulating film. A P-type silicon substrateis commonly used for the substrate 1.

However, the conventional shading films for the solid state image pickupelement, that is, the pure Al films or Al-Si alloy films aredisadvantageous in that heat transfer is generated in Al by theannealing (300 to 400° C.) for eliminating the surface level of thesemiconductor substrate, to thereby generate hillocks on the shadingfilms. When a hillock is protruded from the edge of a light receivingwindow toward the light receiving element side, the light receiving areaof the light receiving element is made smaller than others' so that thesensitivity is lowered. Another disadvantage is to easily produce pinholes resulting in the erroneous electric signal.

(2) Reflection Films

High reflectance is required for reflection films on a substrateconstituting a principal area of an optical recording medium such as anoptical disk or a magneto-optical disk, so that pure Al films have beengenerally used. The pure Al films, however, are poor in corrosionresistance and have a disadvantage of being corroded when placed in airfor a long time, to reduce the reflectance or generate pittingcorrosion, thereby increasing the read error rate in the playback ofinformation (signal).

As a countermeasure therefor, there have been proposed Al alloy filmshaving various compositions, for example, Al alloy films containing Si,Pt or Pd. The proposed alloy films, however, are still insufficient incorrosion resistance to secure the long term reliability in thereproduction of information records in optical recording media. Further,at the film deposition, it is necessary to secure the homogeneity ofalloy composition of the films. In order to achieve this purpose, asputtering process is superior to a vapor deposition process. In thesputtering process, however, the film deposition rate is slow and ittakes a longer time for film deposition in comparison with a vapordeposition process, which lowers the throughput in a film depositionprocess in mass production, and it can be an obstacle for improving theproductivity. Therefore, the conventional Al alloy films have adisadvantage of requiring a long time for the film deposition resultingin the reduced productivity.

(3) Al Alloy Thin Film Line and Electrode Material for SemiconductorDevices

(3)-(a) Al alloy thin films are used as the materials for the electrodesand lines of integrated circuits for general semiconductor devices (asemiconductor device in which elements are formed on a Si wafer), andwhich are divided broadly into two categories, pure Al and Al basedalloys containing Si or Cu.

Pure Al is the most excellent material in the viewpoint of low electricresistivity. However, the pure Al has disadvantage of generatingstress-migration (hereinafter referred to as SM) or electro-migration(hereinafter referred to as EM). SM is the swelling (hillock) and thedisconnection (bad conduction) of the film line caused by stress, andwhich is mainly generated by heating. EM is the disconnection of filmline caused by electric migrations, and which is mainly generated bycurrent-carrying.

Al alloys containing Si or Cu have been developed for improving theabove-mentioned disadvantages, but they are not sufficient in theresistance against SM and EM, and also in corrosion resistance.Accordingly, there has been desired the development of novel materialshaving higher reliability for semiconductor devices.

To obtain the novel material, further alloying can be considered.However, the alloying tends to increase in general the resistivity. Onthe other hand, the allowable upper limit of resistivity tends to belowered by the miniaturization of line (miniaturization in width)accompanied with the higher degree of circuit integration in the recentsemiconductor devices, and simple alloying exceeds the above-mentionedupper limit. Consequently, the development of a novel material forsemiconductor devices are in a difficult situation.

(3)-(b) The materials for electrodes and lines of a TFT used for liquidcrystal displays, etc. are, differently from the materials for theabove-mentioned general semiconductor devices, heated up to acomparatively high temperature (about 400° C. or below 400° C.) in amanufacturing process of a TFT, so that Al based metal materials arepoor in SM resistance. Consequently, refractory materials such as Ti,Cr, Mo, Ta, etc. are often used. However, there is a disadvantage thatthe resistivity is high, and the improvement is desired.

Recently, liquid crystal displays are getting to be larger in sizes fordisplaying larger pictures, and the line connecting between TFT elements(address line) is liable to be lengthened, and the resistance andcapacitance are increased therewith so as to easily cause the delay ofaddress pulses. As a result, the above-mentioned refractory metalmaterials are difficult to be used, and a novel refractory metalmaterial having low resistivity is desired to be developed.

The resistivity of such line is desired to be lower than about 30 μΩcm,and the metals, Au, Cu and Al, satisfy the above-mentioned value. Amongthese metals, Au is difficult to be used because of expensiveness, Cuhas a disadvantage in adhesion and in corrosion resistance. Al has adisadvantage in low melting point and in poor heat resistance, and isliable to occur the short circuits between layers (or between lines) ordisconnections by SM. Accordingly, no one among them can be practicallyused.

Then, multilayer line (composite line), alloying of surface areas ofline by ion implantation (surface alloyed line), etc. have beenproposed. The multilayer line includes both a lower layer of a lowresistance material and an upper layer of a high refractory material, toachieve a composite function of a lower layer (low resistivity) and anupper layer (SM resistance). The surface alloyed line is provided withthe refractory layer on the surface area by ion-implantation ofdifferent elements into a low resistance material, to thus achieve asimilar function to the above-mentioned multilayer line.

In the multilayer line, 2 times of film deposition processes must beperformed, and in some combination of the upper and lower layers, theetching for forming a line pattern must be performed in a differentprocess, to thereby increase the number of processes and to reduce theproductivity. Meanwhile, the surface alloyed line needs a complicatedprocess of ion implantation and is difficult in control of a surfacealloyed layer, to thereby increase the number of processes and to reducethe productivity. Accordingly, there is desired the development of anovel metal material for a TFT which has no such disadvantages asmentioned above, that is, having low resistivity and being excellent inrefractory.

(4) Sputtering Targets for Depositing Al Alloy Films

From the viewpoint of homogeneity of the alloy composition of films, theabove-mentioned Al alloy films is preferably deposited by a sputteringprocess in comparison with a vapor deposition process. In the sputteringprocess, following sputtering targets have been used: (a) a small pieceof a metal (alloy component) such as Cr is placed on a pure Al target;(b) blocks of a pure Al and alloy component are disposed in a mosaicpattern; and (c) powder of a pure Al and alloy component are mixed andsintered.

In the cases of (a) and (b), since there is a difference in thesputtering yield and the radiation angle between an Al and alloycomponent, the composition of the obtained Al alloy films becomessmaller than that of the target (area ratio between an Al and alloycomponent), and the difference varies according to the conditions ofsputtering or to the devices. Therefore, it is difficult to control thecomposition of Al alloy films, and since the above-mentioned area ratiovaries continuously during the usage of a target material, Al alloyfilms of a specified composition is difficult to be obtained. In thecase of (c), since an Al powder comparatively differs from an alloycomponent powder in the specific gravity, it is difficult to mix themhomogeneously and hence to obtain the homogeneous composition of atarget material, so that the Al alloy film composition is liable to beinhomogeneous. Furthermore, the above-mentioned both powders are activeand tend to absorb oxygen strongly, so that the Al alloy films containmuch oxygen thereby degrading the reflectance and also increasing theelectric resistivity.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide Al alloyfilms having such a function as solving the above-mentioneddisadvantages, adapted to be used as

(1) shading films having high reflectance, good adherence, facility foretching, an excellent resistance against hillock, low thermalconductivity, high corrosion resistance, and an excellent resistanceagainst pin holes;

(2) reflection films having high reflectance, high corrosion resistance,and excellent productivity with high film deposition rate in sputtering;

(3) materials for semiconductor devices (thin film line and electrodes)having high refractory (refractory against SM, etc.), refractory againstEM, high corrosion resistance, and low electric resistivity, for use ingeneral semiconductor devices and TFT's without lowering productivity tocope with the narrowing of line width, with the higher degree of circuitintegration of semiconductor devices, and with the lengthening ofaddress line in TPT's accompanied with the development of larger picturesized liquid crystal display; and

(4) melting Al alloy sputtering targets for depositing theabove-mentioned films.

To achieve the above-mentioned objects, according to the presentinvention, there are provided Al alloy films and melting Al alloysputtering targets for depositing the Al alloy films as described in thefollowing.

In claim 1 of the present invention, there is provided a Al alloy filmcomprising an Al alloy containing one kind or two or more kinds of alloycomponents selected from a group of Ti, Zr, Hf, V, Nb, Ta, Cr. Mo and Mnin a total amount of 0.1 to 10 at %.

In claim 2 of the present invention, there is provided an Al alloy filmdefined in the first embodiment, adapted to be used as a reflection filmfor an optical recording medium, or as a shading film for a liquidcrystal display panel or a solid state image pickup device.

In claim 3, there is provided an Al alloy film defined in claim 1,adapted to be used as an Al based ally thin film line or electrodematerial for a semiconductor device.

In claim 7, there is provided a sputtering target comprising a meltingAl based alloy containing one kind or two or more kinds of alloycomponents selected from a group of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mnin a total amount of 0.1 to 10 at %, wherein the intermetallic compoundsbetween Al and the alloy components are homogeneously distributed in theAl matrix.

In claim 8, there is provided a melting Al alloy sputtering target fordepositing the film defined in claim 7, wherein the above-mentionedintermetallic compounds are needle-shaped and the lateral length of themare shorter than 200 μm.

In claim 9, there is provided a melting Al alloy sputtering target fordepositing the film defined in claims 7 and 8, wherein the oxygencontent in the melting Al alloy is lower than 400 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and aspects of the invention will be become apparent fromthe following description of embodiments with reference to theaccompanying drawings:

FIG. 1 is a diagram showing the relation between the content of Ti, Zror Hf in a sputtering target material comprising a melting Al alloyaccording to the Example 1 and the reflectance of the reflection filmsobtained from the sputtering of the target material;

FIG. 2 is a diagram showing the relation between the content of Ta, Nbor V in a sputtering target material of a melting Al alloy according tothe Example 1 and the reflectance of the reflection films;

FIG. 3 is a diagram showing the relation between the content of Cr, Moor Mn in a sputtering target material of a melting Al alloy according tothe Example 1 and the reflectance of the reflection films;

FIG. 4 is a diagram showing the relation between the content of Ti, Zror Hf in a sputtering target material of a melting Al alloy according tothe example 2 and the quantities of decrease in the reflectance of thereflection films;

FIG. 5 is a diagram showing the relation between the content of V, Zr orHf in a sputtering target material of a melting Al alloy according tothe Example 2 and the quantities of decrease in the reflectance of thereflection films;

FIG. 6 is a diagram showing the relation between the content of Cr, Moor Mn in a sputtering target material of a melting Al alloy according tothe example 2 and the quantities of decrease in the reflectance of thereflection films;

FIG. 7 is a diagram showing the relation between the content of Cu, Ti,Zr or Hf in a sputtering target material of a melting Al alloy accordingto the example 3 and the thermal conductivity of the shading filmsobtained from the sputtering of the target material;

FIG. 8 is a diagram showing the relation between the content of V, Nb orTa in a sputtering target material of a melting Al alloy according tothe example 3 and the thermal conductivity of the shading films;

FIG. 9 is a diagram showing the relation between the content of Cr, Moor Mn in a sputtering target material of a melting Al alloy according tothe example 3 and the thermal conductivity of the shading films;

FIG. 10 is a diagram showing the relation between the content of Hf orNb in the sputtering target material of a melting ternary system Alalloy according to the example 4 and the quantities of decrease in thereflectance of the films;

FIGS. 11 and 12 are diagrams each showing the relation between thecontent of Hf or Nb in a sputtering target material of a melting ternarysystem Al alloy according the example 5 and the thermal conductivity ofthe films;

FIG. 13 is a diagram showing the relation between the content of Hf orNb in a sputtering target material of a melting quaternary system Alalloy according to the Example 6 and the quantity of decrease in thereflectance of the films;

FIG. 14 is a diagram showing the relation between the content of Hf orNb in a sputtering target material of a melting quaternary system Alalloy according to the Example 6 and the thermal conductivity of thefilms;

FIG. 15 is a diagram showing the relation between the content of Hf orNb in a sputtering target material of a melting quinary system Al alloyaccording to the example 7 and the quantity of decrease in thereflectance of the films;

FIG. 16 is a diagram showing the relation between the content of Hf orNb in a sputtering target material of a melting quinary system Al alloyaccording to the example 7 and the thermal conductivity of the films;and

FIG. 17 is a sectional view showing the principal are of a conventionalsolid state image pickup device (element).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The exemplary embodiments according to the present invention will bedescribed with reference to the drawings.

First, there were manufactured Al alloy sputtering targets comprising Alcontaining various kinds of elements. Next, with the use of the abovetargets, many kinds of Al alloy shading films were deposited by asputtering process. Then, the following characteristics wereinvestigated: the characteristics required for shading films such as thecomposition, reflectance, corrosion resistance, resistance againsthillock, adherence, thermal conductivity, or etching property; thecharacteristics required for a semiconductor material (Al alloy line andelectrode materials) such as refractory (resistance against SM, etc.),and resistance against EM etc.; and the characteristics required forreflection films. As the result, it was found that the addition of Ti,Zr, Hf, V, Nb, Ta, Cr, Mo and Mn to Al was most effective for theimprovement of the above-mentioned characteristics, and also that Alalloy films containing these elements have excellent characteristics asshading films, reflection films and semiconductor materials.

(1) Since an Al alloy film according to the present invention comprisesan Al alloy containing one kind or two or more kinds of alloy componentsselected from a group of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn(hereinafter referred to as Ti, etc.) in a total amount of 0.1 to 10 at%, it achieves the characteristics of Al or of an Al alloy, and at thesame time has high reflectance, good adhesion and excellent etchingcharacteristics.

In addition of Ti, etc. to Al, with the increase in the added amount,resistance against hillock and corrosion resistance are upgraded andthermal conductivity becomes low. Therefore, the Al alloy film accordingto the present invention has excellent in the resistance against hillockand low thermal conductivity, and further is excellent in corrosionresistance which prevents the occurrence of pin holes in the film. Inthis case, it is necessary to control the added amount (content) of Ti,etc. to be in the range of 0.1 to 10 at % in a total amount. The reasonsare as mentioned below.

When the content of Ti, etc. is less than 0.1 at %, resistance againsthillock and corrosion resistance are insufficient and thermalconductivity is not sufficiently low. When the content of Ti, etc. ismore than 10 at %, the reflectance is lowered and the alloy tends toabsorb heat easily by the radiation of the light and also etchingbecomes difficult. In the case of wet etching, in particular, when thetotal amount of alloy components is more than 10 at %, etching residueis produced and perfect etching cannot be performed.

As described in the above, the Al alloy film according to the presentinvention has high reflectance, good adhesion, easy etching property,excellent resistance against hillock, low thermal conductivity,excellent corrosion resistance, and property to suppress pin holes, tothereby achieve the excellent characteristics as a shading film.

(2) The Ti, etc. containing Al alloy film has high reflectance,excellent corrosion resistance, and high film deposition rate insputtering, namely, high productivity, to thereby achieve excellentcharacteristics as a reflection film. In this case, when the amount ofTi, etc. is less than 0.1 at %, the progress of film deposition rate isalmost not observed. When the amount of Ti. etc. is more than 10 at %,the lowering of reflectance and the occurrence of read errors can beobserved. Accordingly, the total amount of Ti, etc. is limited withinthe range of 0.1 to 10 at %.

(3) In the Ti, etc. containing Al alloy film, refractory (resistanceagainst SM, etc.) and resistance against EM are upgraded. Thesecharacteristics are better than those of the conventional pure Al or Alalloy containing Si or Cu, and are in a similar level to those ofrefractory metal materials such as Ti, Cr, Mo, Ta, etc. The electricresistivity is improved to be lower than about 30 μΩcm, and thecorrosion resistance is better than that of a pure Al. Further, it canbe manufactured in a similar way to that of the conventional Al alloyfilm containing Si, etc., so that there is no fear to lower productivitywhich occurs in the case of composite line or in the case of surfacealloyed line by ion implantation. Therefore, the Al alloy film canexhibit excellent functions as thin film line or electrode material fora semiconductor device. In this case, when the amount of Ti, etc. isless than 0.1 at %, resistance against SM and corrosion resistance areinsufficient. When the amount of Ti, etc. is more than 10 at %, electricresistivity becomes higher than about 30 μΩcm. Consequently, the contentof Ti, etc. is limited within the range of 0.1 to 10 at %.

(4) An optimum ratio of added components differs a little by usesintended by the present invention, as explained in the following.

When one kind or two or more kinds of alloy components selected from agroup of Ti, Cr and Ta are added to Al, the obtained alloy film hasparticularly excellent resistance against hillock, low thermalconductivity, excellent corrosion resistance, and property to suppresspin holes, thus being preferably usable as a shading film for a liquidcrystal display panel or for a solid state image pickup device.

When one kind or two or more kinds of alloy components selected from agroup of Ti, Ta, Mn, Cr and Zr are added to Al, the obtained alloy filmis excellent in refractory (resistance against SM, etc.), in resistanceagainst EM, and in corrosion resistance, and also low in electricresistivity to be 10 μΩcm or less, thus being preferably usable forgeneral semiconductor devices and for TFT's. Furthermore, it can copewith the narrowing of line width accompanied with the development tohigher degrees of circuit integration of semiconductor devices in recentyears, and it also can cope with the lengthening of address line ofTFT's accompanied with the development toward larger screen sizes ofliquid crystal display panels.

Mn does not influence upon the film deposition rate in sputtering, sothat the productivity of an Al alloy film containing Mn is similar tothat of the pure Al film. Since the difference between the meltingpoints of Al and Mn is comparatively small, the control of melting andmelting metal composition are easier in comparison with the case where atransition element of IVa or Va group is added, and therefore, thehomogeneity in composition of a melting Al alloy target is excellent,which makes it possible to stably obtain an Al alloy film of a specifiedcomposition and of an excellent homogeneity in composition.

Therefore, an Al alloy film containing Mn has high reflectance, highcorrosion resistance, and low thermal conductivity, and also it isexcellent in homogeneity of composition and in productivity.

When, besides Mn, one kind or two or more kinds of alloy componentsselected from a group of Hf and Ta (hereinafter referred to as Hf, etc.)are added, the film deposition rate in sputtering is remarkablyimproved. In addition, the effect of Hf and Ta can be also obtained byusing Ti, Zr, V, Nb, Cr and Mo, besides Mn.

(5) The melting Al alloy sputtering target for depositing thin filmsaccording to the present invention is, as mentioned in the above, amelting Al alloy containing one kind or two or more kinds of alloycomponents selected from a group of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn(Ti, etc.) in a total amount of 0.1 to 10 at %. That is, theabove-mentioned Al alloy is manufactured through the processes ofmelting and casting, so that part of the Ti, etc. is dissolved in asolid solution in the Al matrix, and most of them exist in the state ofintermetallic compound with Al. The distribution of Ti, etc. in a solidsolution is homogeneous, and the intermetallic compound is alsohomogeneously distributed. Such a homogeneously distributed state can beobtained easily. Thereby, the Ti, etc. is homogeneously distributed inan Al alloy, thus forming a target material containing Ti, etc.homogeneously distributed in the Al matrix.

Since such a target material has a homogeneous composition, the changein the composition with time during operation does not occur, and alsosince the sputtering yield is a constant, the composition of a targetalmost is identical to that of an alloy film obtained from the target.Therefore, it is easy to adjust the composition of an alloy film, andconsequently an alloy film having a specified composition can be stablyobtained. The above-mentioned target material is manufactured through amelting process, so that the oxygen content can be controlled in a lowlevel, to thereby secure an alloy film of low oxygen content and of highreflectance.

The reasons why the content of Ti, etc. is limited in the range of 0.1to 10 at % is similar to the reasons for limiting the content of alloycomponents in the above-mentioned Al alloy film. When the content isless than 0.1 at %, the effect of improving corrosion resistance issmall, and when the content is more than 10 at %, the necessaryreflectance of more than 70% cannot be secured as shown in FIGS. 1 and2.

When the oxygen content of a melting Al based alloy is more than 400ppm, the reflectance starts to be lowered, so that it is desirable tolimit the oxygen content less than 400 ppm.

When the sizes of the intermetallic compound are larger than 200 μm, thealloy film composition is different from that of the target alloy, butwhen the sizes are smaller than 200 μm, the above-mentioned differencealmost disappears and the alloy film composition can be easily adjusted.

In order to make the size of the intermetallic compound less than 200μm, there may be rapidly cooled the molten metal obtained by a meltingmethod in which Al and Ti, etc. are homogeneously mixed. There areseveral methods of rapid cooling: molten metals are cast in a watercooled copper mold or in a mold having a large cooling capacity; moltenmetals are continuously cast in a water cooled mold: molten metals arepoured between two rotating rollers to produce thin plates; or moltenmetals are atomized by an inert gas

EXAMPLE 1

An alloy of 4 kg was molten by induction heating in vacuum and was thencast in a water cooled copper mold, to obtain a binary system Al alloyingot containing Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn in amounts of 0.2to 10 at %, respectively. Subsequently, by using the ingot, a sputteringtarget was picked from the ingot and Al alloy films (reflection films)of 1000 Å thickness were deposited on transparent polycarbonate resinsubstrates having the thickness of 1.2 mm by a DC magnetron sputteringprocess. Samples were prepared by applying protection films (10 μmthick) of acrylic resin over the reflection films by spin coating.

The reflectance of the above-mentioned samples were measured from theside thereof with use of a laser beam having a wavelength of 780 nm. Theresults are shown in FIGS. 1 to 3. In all alloy films, the reflectancethereof was decreased with the increase in the amount of added elements(contents). However, they showed high reflectance (initial reflectance)of more than 70% so far as the contents were less than 10 at %.

EXAMPLE 2

As for the samples obtained in the example 1, a PCT (Pressure CookerTest) was carried out at 105° C., at 1.2 atm and in related humidity of100% to evaluate the corrosion resistance of reflection films based onthe quantity of decrease in reflectance (decreasing factor). There areshown, in FIGS. 4 to 6, the quantities of decrease in reflectance during30 hours after the start of the PCT. The quantity of decrease inreflectance was remarkably improved by the addition of Ti, Zr, Hf, V,Nb, Ta, Cr, Mo and Mn. It shows that the samples are excellent incorrosion resistance.

EXAMPLE 3

Al alloy films of 10 μm thickness (shading films) were deposited using asimilar target and by a similar sputtering process to those in theexample 1. As for these samples, thermal conductivity of shading filmswas measured by AC calorimetric method. The results are shown in FIGS. 7to 9. The thermal conductivity is remarkably lowered by the addition ofTi, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn. The lowering effect is larger in afilm state, differently from that in a bulk state.

As a comparative example, a similar measurement was made about an Al-Cualloy film, and the result showed that a lowering tendency of thethermal conductivity in a film state was similar to that in a bulkstate, and the remarkable lowering in thermal conductivity was notobserved.

EXAMPLE 4

Among the above-mentioned binary system Al alloys, an Al-2 at % Ti alloyand an Al-2 at % Ta alloy were selected as typical examples, and Hf orNb containing ternary system Al alloy films were deposited and aresubjected to a similar PCT as in the example 2. The results are shown inFIG. 10. By further addition of Hf or Nb, the quantity of decrease inreflectance showed a tendency to lower, thus improving corrosionresistance.

This example show one of corrosion resistance of ternary system Alalloy-films. Since the effect of an added element on the corrosionresistance has an additive property, the above-mentioned results holdtrue in all combinations of added elements.

EXAMPLE 5

As for ternary system Al alloy films described in the example 4, thermalconductivity of shading films was measured by AC calorimetric method ina similar way to the case of the Example 5. The results are shown inFIGS. 11 and 12. When Hf or Nb is further added to Al-2 at % Ti alloy orAl-2 at % Ta alloy, the thermal conductivity showed a tendency todecrease further. The effect of adding such as Hf or Nb is constantindependent of kinds of the binary system Al alloys (kinds and contentsof alloyed elements), and the effect is not influenced by the kinds ofAl alloys.

EXAMPLE 6

There were deposited the films of quaternary system Al alloy obtained byadding further Hf or Nb to an Al-2 at %-2 at % Ta alloy and a PCT andthermal conductivity measurement were carried out in a similar way as inthe Examples 2 and 3. The results are shown in FIGS. 13 and 14. Thethermal conductivity showed a tendency to decrease with the increase inthe added amount of Hf or Nb.

EXAMPLE 7

There were deposited the films of quinary system Al alloy films obtainedby adding further Hf and Nb to an Al-2 at %-2 at % Ta alloy, and asimilar measurement was carried out as in the example 6. The results areshown in FIGS. 15 and 16. The change in thermal conductivity with theincrease in the added amount of Hf and Nb was small.

COMPARATIVE EXAMPLE 1

After the mixing of a pure Al powder and Ti powder with a V mixer, themixture was sintered at 450° C. by HIP method, to prepare a sputteringtarget material comprising binary system Al group sintered materialcontaining 2 at % of Ti, and then oxygen content was analyzed.Reflection films were deposited using the target material in a similarway to that in the example 1. The oxygen content of the target materialwas 1100 ppm, and the reflectance of the reflection film was 60%.

On the other hand, in the Example 1, the oxygen content of a sputteringtarget material comprising the binary system Al group alloy containing 2at % of Ti was 100 ppm. The reflectance of reflection films obtainedfrom the target material was 83%, which is a very high value differentfrom the reflectance of 60% in the above-mentioned comparativeexample 1. This is due to the difference in oxygen contents of bothmaterials.

What is claimed is:
 1. A sputtering target, comprising Al and 0.1 to 10at. % of at least one alloy component selected from the group consistingof Ti, Zr, and Hf, wherein said target comprises one or moreintermetallic compounds comprising said at least one alloy component andAl, homogeneously distributed in said Al, and said one or moreintermetallic compounds are needle-shaped and have a lateral dimensionof less than 200 μm.
 2. The sputtering target according to claim 1,wherein the alloy compound is Ti.
 3. The sputtering target according toclaim 1, wherein the alloy compound is Zr.
 4. The sputtering targetaccording to claim 1, wherein the alloy compound is Hf.
 5. A sputteringtarget, comprising Al and 0.1 to 10 at. % of at least one alloycomponent selected from the group consisting of Zr and Hf, wherein saidtarget comprises one or more intermetallic compounds comprising said atleast one alloy component and Al, homogeneously distributed in said Al,and said one or more intermetallic compounds are needle-shaped and havea lateral dimension of less than 200 μm.
 6. The sputtering targetaccording to claim 5, wherein the alloy compound is Zr.
 7. Thesputtering target according to claim 5, wherein the alloy compound isHf.
 8. A sputtering target, consisting essentially of Al and 0.1 to 10at. % of at least one alloy component selected from the group consistingof Ti, Zr, and Hf, wherein said target consists essentially of one ormore intermetallic compounds comprising said at least one alloycomponent and Al, homogeneously distributed in said Al, and said one ormore intermetallic compounds are needle-shaped and have a lateraldimension of less than 200 μm.
 9. The sputtering target according toclaim 8, wherein the alloy compound is Ti.
 10. The sputtering targetaccording to claim 8, wherein the alloy compound is Zr.
 11. Thesputtering target according to claim 8, wherein the alloy compound isHf.